say i have a database, and in this database i have lots of records. Now, say that i want to modify one of these records, i wouldnt have to delete this record would i? do i just do the standard INSERT INTO query, while specifying the same unique key? or what?

No, use the SQL command 'UPDATE' to modify an existing record in the database. Just be specific in the where clause to ensure you will only modify the number of records intended (usually one) and no others.

I recommend the book: SQL: The Complete Reference by Groff and Weinberg (Osborne/McGraw Hill Publishing). It is comprehensive and will address most any SQL issue you have a question about.